Ventilating device and like air supply and distributing device



T. C. FlTT Nov. 18, 1952 VENTILATING DEVICE AND LIKE AIR SUPPLY AND DISTRIBUTING DEVICE Filed May 5, 1948 4 Sheets-Sheet l lw f/vraz 5 7/2/1445 5. Firr T. C. FlTT Nov. 18, 1952 VENTILATING DEVICE AND LIKE AIR SUPPLY AND DISTRIBUTING DEVICE 4 Sheets-Sheet 2 Filed May 5, 1948 WV'FA/IWF 7/70/1445 C. 577

T. C. FlTT Noy. 18, 1952 VENTILATING DEVICE AND LIKE AIR SUPPLY AND DISTRIBUTING DEVICE Filed May 3, 1948 4 Sheets-Sheet 3 Nov. 18, 1952 T. c. FITT 2,61

VENTILATING DEVICE AND LIKE AIR SUPPLY AND DISTRIBUTING DEVICE Filed May 3, 1948 4 Sheets-Sheet 4 Patented Nov. 18, 1952 VENTILATING DEVICE AND LIKE AIR-SUP- LY .AND DISTRIBUTING DEVICE Thomas Charles Fitt, vBirmingham, England Application May .3, 1948, Serial.N0. 24,7:97 .In Great Britain July 1, .1943

13 Claims.

The esen in ention concerns impro m in. g i latins to en ilation for bu l gs, airra t h s n like nc o ed paces- The object o t e nvention is to supply a r to a ro m o h m e or t e tract it from a room or chamber or both supply and extract air in such a way that no readily perceptible draught is created even thou h the air in the chamber may be changed several times per hour.

The invention consists essent ially in providing a. diffuser or like device which so distributes the pressure of air emanating from or drawn to the di fuser that it is substantially uniform at the level of the heads of peopleworking in the room r. hambenif any h n with a tendency f r h ir a suc e el t mo e in the opposite direction to that in which the air emerges from or is driven nt the diff ser,-

Qne object of the invention is a method of ventilation to bring about the above results while a further object is a diffuser which enables the ventilation to be effected in accordance with the method.

Referring to the drawings:

Figures 1 and 2 illustrate a sectional elevation and half plan of a preferred construction of diffuser in accordance with the invention.

Figures 3 and {l illustrate a plan and side view of'a form of screen device as employed in the diffuser illustrated in Figures 1 and 2, and

Fi ures 5 and 6 illustrate in plan and side view an alternative form of screen to that illustrated in' Figures 3 and 4.

Figure '7 illustrates a section of a diffuser with a different form of screen to that illustrated in Figures 3, to 6.

Figure li'illustrates by way of example diffusers asus ed in practice to ventilate a room.

Figure Qillustrates a diffuser for extracting air from'a room.

"Referring to Figure 8, I I represents an air conduit through which air is fed from a blower I2 to conduits I3 and I4 which conduits terminate in diffusers l5, and I6 such as illustrated in Figures 1, 2 and '7 and described more particularly hereinafter. These diffusers are arranged at a convenient height above the floor on which devices such as IT and it are located at which operatives work. Such devices, for instance, in a laundry. may be Washing or ironing machines, from which clouds of steam may emerge. when'in use. In such a case the height of the diffusers I5 and I6 from the floor I9 might be between 7 and 10 feet while the. operatives? heights when standing would be about five to six feet. The

difiusers I5 and I6 serve to distribute air from the conduit III in such a way that 'thegpressure exerted along surfaces at a constant distance from the outlet end of the diffusers is slightly'le'ss' at the axes 22 and'23 of the diffusers that it is, for

the diffuser. This has the effect that escaping steam from devices l1 and I8 is drawn upwards and so away from the faces of the users. v

The arrows indicate generally the direction of flow of air. It will be noted that this effect is quite contrary to what would be expected and also that what would happer if the diffuser was of the conventional type that is to say not fitted with a special screen such as illustrated in Figures 3 to 6 in detail, or as shown in Figures 1, 2, 7 and 9 in position. It will be obvious that with air continuously flowing into the room there will be a tendency for the pressure in the room to rise unless means are provided for permitting the escape of the air. It of course frequently happens in many cases that the air escapes under doors, chimneys or the like,- although special; suction means may be provided as illustrated in Figure 9 and shown in position in Figure 8- under the reference 24. The effect of such suction device fitted as illustrated in Figure 8 is to draw air out of the room but at a substantially uniformly distributed pressure over a wide area at a distance of a foot.

or so from the suction device the actual move ment of the air being almost imperceptible. It is therefore possible by means of this invention to effectively ventilate a room and to abstract therefrom steam or noxious gases by driving I them away from the faces of the operatives who The reference to the movement of the air being v almost imperceptible is intended to convey that the normal means for testing such movements such as feeling; movement of light solid substances or deflection of thin paper or the like.

does not show any response, but smoke, steam or the like visible means having a specific gravity not appreciably greater than that of air to enable the direction of movement to be observed.

Figure 7 illustrates a construction of the diffuser which was found to give quite satisfactory results. The main part of the diffuser is a well known construction consisting of a series of nested truncated cones 25, 26, 2?, 23, 29, 3B and 3| so arranged as to form diverging passages from the axis 32 to the outer peripheral wall 33.

The inner ends of the truncated cones terminate on a surface 34 concave with respect to the conduit through which air is received.

Conveniently the base of the central cone is furthest from the plane 36 in which the conduit 3'! to which the diffuser is attached terminates, while the base of the other cone is successively nearer to the plane 36 with the base of the outer cone nearest as shown.

The sloping surfaces of the cones and their dimensions are such as to provide diverging passages of widths more or less equal.

Awire screen 35 formed so as to have a coarse mesh and shaped to conform with the surface 34 is fitted so as to lie on the inner ends of the cones 25 to 3|.

It is important that the screen should not unduly restrict the total quantity of air flowing through the diffuser and for that reason the dimensions of the wire preferably lie between the following limits, namely, 18 to 22 S. W. G. wire and 7 to 10 meshes to the inch for the coarseness of the screen. The best results attained for ordinary room ventilation were with a wire mesh screen of 21 S. W. G. woven to provide 7 meshes per linear inch although a wire of 19 S. W. woven to provide 9 meshes to the linear inch also serves well.

The apertures in the screen are small in comparison with the gaps between the inner ends of adjacent plates. The mesh of the screen however, is not critical over a wide range but is limited by considerations of efficiency. Thus with an inlet diffuser discharging from a height of feet an average linear velocity of 1000 feet per inch at substantially uniform distribution at head level is attained if the gauze has 6 meshes per linear inch. If the diffuser is arranged at a more normal level of 7 to 10 feet and the rate of discharging has an average velocity of 600 feet per inch then an 8 mesh gauze is satisfactory. For a diffuser discharging at mouth level at a rate of 200 feet per minute for example, for the ventilation of noxious gas, 20 mesh gauze is suitable. In the latter case it is preferable to provide in the diffuser means for cleaning the fine gauze such as a rotary brush acting on that face of the;

gauze which faces the direction of air flow.

It will be apparent that if a different form of distribution is required this result can be achieved by varying the mesh of the gauze so that the section they might be elliptical or polygonal.

Preferably they are symmetrical about a common axis but this is not essential.

Referring to Figures 3 and 4 a different construction of screen is provided in place of the wire mesh screen of Figure '7. This screen consists of a number of frusto-conical strips 3'1, 38, 39, 49, 5| and 42 formed of metal, plastic or similar material and secured together on curved wires or rods which are substantially radial in plan view.

In Figures 1 and 2 the screen illustrated in Figures 3 and 4 is shown located in a diffuser of similar construction except for the coarse wire screen to that illustrated in Figure 7 from which it will be seen that the frusto-conical strip 37 is arranged to lie between the cones 30 and 3! and to have an inclination intermediate the inclination of the two cones 30 and 3|. Similarly, the strips 38, 39, 40, 4! and 42 are arranged to lie intermediate the pairs of cones 30 and 29. 23 and 28, 28 and 21, 21 and 26, 26 and 25, respectively, and in which case the inclination is such as'to have an inclination intermediate of the walls of the cones on each side of it so as to offer the smallest dimension, namely, the thickness of the metal of the strip to the flow of air. Preferably the position of the strips is not on the mid-way point between two walls but nearer to the outer wall the distance from the two walls conveniently being in the ratio of 2 to l. The width of the strips 31 to 42 is a small fraction of the length of the passages between successive cones.

With this arrangement the resistances to air flow is very much reduced compared with the wire screen of 35 but the same general effect as.

regards the air circulation to that in rooms fitted with the diffuser of Figure 7 is obtained so that there is an upward current below the diffuser whenair is being blown into the room from the diffuser at a comparatively short distance fIOlIL the diffuser.

It will be noted that there is no frustoconical strip shown in the central passage of cone 25. By reference to the plan view in Figure 2 it will be seen that the radial wires 43 extend into the centre and across the central passage thereby exercising the required screening effect which in respect of the other passages is mainly provided by the frusto-conical strips. 1

As the diffusers are made in widely differing sizes according the purpose for which they are used being fitted to ducts from as small as 1 /2 inches diameter to as large as 5 inches diameter finest gauze may be at the periphery and the mesh becoming coarser at the successive chan- I nels until the coarsest mesh is reached at the 1 Naturally the variations in the mesh depend upon the effect it is desired to produce provided that those variacentral channel or vice versa.

tions are not sufficient to interfere with the general direction of air streams which is an integral part of the present invention. Instead of the cones '25 to 3| it will be clear that the passages I or channels may be formed in other ways. For instance, instead of the cones being of circular the number and dispositionof the frusto-conical strips may be varied to suit circumstances and Figures 5 and 6 illustrate a construction in which as many as 11 frusto-conical strips 43 to 53 may be employed for a diffuser which is assumed to be made up of 7 frusto-cones shown in chain dotted lines 54, 55, 56, 57, 58 and 59 in Figure 6. In this case it will be noted that there are two strips between every pair of cones except cones 59 and- 50 where there is only one strip 53. The exact number in any particular case will be adjusted according to circumstances.

tween adjacent strips or between strips and the adjacent walls of the frusto-cones the maximum spacing should not exceed one inch and as a' been found to give the most satisfactory results in the majority of cases.

In the construction of Figures 3, 4, 5 and 6 the Generally speaking the spacing of the partsshould be such that beirusto-conical strips may be secured to radial mportsmt:bnmetamny" brazing'ami the pafts aimstmteaz' Figures ,5 atid 6 -ay -be itl'i'e'r densely-fitted to thditf-u er- 01 n1 9' be rig-idly tseeuted thereto Fr simplification-an c'onstrud tiom showni-in Figure ij thefiiisto-oonical strips are: mlii-mauu pxor a nun' tier ornarts exte'ndiing' between adjacent radial rods 43:1eavin'g gaps 55- by :which the I scren may be fitted difiiiser' liavin'g radially disposed I supporting plates ib'etween the senescence-1am!)to st, ot course aswan alternative' slots could be provided-in these racliaizipl'ates instead of dividing the' stri-p; -As an. alternative to a series of frusto-conical strips nn equtvalent result maybe attaind' by a spirallyz shaped strip. In -eithercase"*the'sestr'ips b'finecuredf by soldering; brazing' or' like means":t6 the -radial sp'okes fi which serve to space such parts 'o'r :str-ips a" desired distance apart, The spacingof -'the-strip may be increased asz-tne size: of the'iiuet and the-size and-seating a! th'e cbnes torming i the "bailles' increases while stint-giving the I desiredeffeet o-t uniform dis tribution of pressure over 'awide are'a alt 'a' -short distance: from -the -outei 'end of the' baiile'; 'I-he ammo: thestrip may be' quit small in each case not more than an inch 'andin smaller oasesxnot more than /g-mf an inch While the thickness of the material formingthe strip can be -aspossib1e having regard to its meehanical' strength being'sufficient'to ensure the strip mll not be readily.-

normal :usages deformed or defle'otedin rts'ifls a general guide to the construction of satisiactoryidifiusers in accordance with'the invention 5; des'oribtion will be given with terminalsof a lan'e 'siztldifius'el' suitable f or fitt'ingtd a duct W356" diameteranda difiuser suitable 'forfitting td a duotethy -inchesdiameterisrwith a duct of it'fi diameter; 7 battles in the shai 'e oLfrusto-cbnes are provided, the outer one ektending from the circumierence 01 the dubt forwards f 0119a and outward'sto- 8 '9 diameter,

the second eiztending forwards for 8-fi%""-from a diameter'oi 3'-0'-' -toardiameter'oi 8' with its-open amma plane 2 intront oi} the plane-of the teen 'endA of th outer bafile; the third extending forwards fo'r-9-% -from a diameter- 0f 2 5 to a diameter of 6" 9' withits open end in a plane 2' gum front of the-plane:otthe open end of tli seeond -baffi'e', the iourth extending forwards mm 9% from adi'ameter 29 A to a diamete oil-'3 with 'its openend in a plane 2% '--in front of the plane of the-openendiofthe third' baiile} open-fend in a' plane ---1 2/; f A in front l of the plane f -the-. op'en end-.-of; the iourth baffle; the 'sixth =e'x= tendingforwards fo-r 11'-'-=froma diameter of 8 %h;to a di'ameter of 21 w-ith 'its open end I alplane Of= *1 in front ofit-he planeof 'th open'enddf the fifth baiile and theseventh ex tending forwards 'from 11% -'-'froni a diameter qfr3 f to -a 'diameter'of 11%" with its open 'end in a'plane in front of -the plane of the open mam the sixth baffle. To such a baffle arrange ment according to the invention,- between the base and next; inner' bafile as fitted a 's't'rip 0f;

frusto-conical shape at the *innerend *of the I baffles so asto divide the entrance to the battles v intd two par-ts being nearer to the outerbafil'e than the inner in the ratio of approximately l tci 2. --The-inclination-of the cone to be such that the-'striplies so as to ofl'er 'substantia'lly mini niurn rsis tance to --the air stream, the depth ofi t at o the w nes set a ed c to a diameter of 2 /4 with its open end irr' a mane 74 *in from of the plane or the open 'he tsecdndbaifirthe fourth exte'nding we for- 5a" tram a-dian'i'et'er df tzw M 'ameter or 1%; with -it's open end in ama'rieW/i" the axis o'f the diifusiisin-lihe with the the conduit butthis is notessential-J If v clined it may be desirable to var-y the sdreen acdrding as --'to'- whether thepassages are rnore oF less 'i-nclined to the directionof" air new the conduit although actuallyit'has been found that the desired distribution and fiow'"'of' airin aoordance with the invention'can'be produced with "the axisof the conduit at right to the axis of 'the diffuser. I

used for the air conditioning' of "a m n, hea I0 and H may be provided-such'a's sh "r1 in ure- 8 in the' 'oonduits l 3*ai1d "I t res ie'li-Itively,-in this case the devices-'11 I8- {night be des atWliih clerks "are working" and the hea ted adiiiittd ta king the' urse described does not travels round and heats the ro'onf unifor I hi's application-"is a continuation flih 1 93-19441 now-abandoned? T"- I l 5.x. I .1 ix Aldifiuser for ventilating and like purposes comprising a tlu'rality bf partitidns forifii o'f he p'assage'forn'iin'E} liartition's distance from the "difiuser *and irnniediatelyTr; front thereof isin" the opposite 'direeft'ioitothafi offfhe -air flowing through the'd-ifiuser' an w m s' r omeowne 7 r 2. A diffuser for ventilating and like purposes comprising a plurality of partitions forming adjacent diverging passages and dividing means consisting of a framework of transverse members narrow with respect to the passages located at the inner ends of the partitions which are nearest together and mounted in the inner ends of the passages intermediate the inner edges of the passage forming partitions and with their inner ends flush with the inner ends of the passage forming partitions, which cause the air streams through the entrance of the passages to be broken up so that the flow of air across the outlet end of each of the passages is substantially unidirectional while the direction of flow at some distance from the diffuser and immediately in front thereof is in the opposite direction to that of the air flowing through the diffuser and to the sides of the diffuser.

3. A diffuser for ventilating and like purposes comprising a plurality of partitions forming adjacent diverging passages and dividing means consisting of a framework of elongated strips of substantially rigid material lying normal to and mounted in the inner ends of the passages intermediate the inner edges of the passage forming partitions and with their inner ends flush with the inner ends of the passage forming partitions, so as to cause the air streams to be broken up while permitting them to reunite at the outlet end so that the flow of air across the outlet end of each of the passages is substantially unidirectional while the direction of flow at some distance from the diffuser and immediately in front thereof is in the opposite direction to that of the air flowing through the diffuser and to the sides of the diffuser.

4. A diffuser as claimed in claim 3 in which the elongated strips extend at a substantially constant distance from the partitions forming'he passage ways.

5. A diffuser as claimed in claim 3 in which the elongated strips extend at a substantially constant distance from the partitions forming the passages which is greater from the partition which is more diverging than it is from the partition which is less diverging.

6. A diffuser as claimed in claim 3 in which the width of the elongated strips is such that the strips extend from the inner end of the passages into the passages to a distance within the passages which is less than one quarter of the length of the passage waysv 7. A diffuser for ventilating and like purposes having a narrow inner end comprising a plurality of partitions positioned with their inner ends defining a concave surface at the narrow end of the difiuser, and extending to an outer end at least double the size of the inner end to form a series of diverging annular passages of successively greater cross section and dividing means in the form of a framework of transverse members narrow with respect to the width of the passages, mounted in the inner ends of the passages intermediate the inner edges of the passage forming partitions and with their inner ends flush with the inner ends of the passage forming partititons, to cause airstreams entering said narrow end to be split up and to reunite so that the flow of air across the outlet end of each of the passage ways is substantially unidirectional while the air streams emanating from the various passages extend further in the direction of passages of greater cross section and less in the direction of passages having smaller cross section whereby 8 I the flow of air at some distance and immediately in front of the diffuser is so slight as to be almost imperceptible while the direction of flow is in the opposite direction to the direction of airficwing through the diffuser and to the sides thereof;

8. A diffuser as claimed in claim 7 in which the framework is formed of elongated narrow strips of substantially rigid material secured so as to lie with their thinnest dimension normal to the air stream and to extend from the entrance of the passage ways inwards to an extent which is less than one quarter of the length of the passage way.

9. A diffuser as claimed in claim 8 in which the framework is formed of radial wires shaped to conform to said concave surface and elongated narrow strips of metal supported on said wire, the central radial wires extending over the central passage while the elongated narrow strips of metal having their thinnest dimension normal to the air stream divide up the narrow entrance to the annular passages into a limited number of substantially annular portions.

10. A diffuser for ventilating and like purposes comprising a plurality of partitions in the form of truncated coaxial cones of successively greater cross section having their narrow ends positioned to define a surface forming a segment of a sphere and concave with respect to the narrow end of the diffuser and a framework formed of radial wires adapted to conform to the curvature of said surface, and supporting spaced narrow elongated strips of metal in annular formation in the upper ends of the passages intermediate the upper edges of the passage formin partitions and with their upper ends flush with the upper ends of the passage forming partitions, to divide the passages between the cones at their narrowest end and located to offer approximately minimum resistance to flow of air, the action of the framework being such as to cause the move-f ment of air at the outlet end of the passage ways to be substantially unidirectional while the direction of flow at some distance from the immediate front of the diffuser to be so slight as to be almost imperceptible and the direction of flow to be opposite that passing through the central cone and at the sides of the diffuser.

11. A ventilating system comprising an air conduit, a diffuser connected to the end of an extension of said conduit, a blower adapted to cause air to flow from the conduit through the diffuser, the diffuser comprising a series of partitions each' of the shape of a frustrum of a cone and having successively wider cross section so as to leave diverging passages between said partitions to permit air being directed in expanding streams" and dividing means comprising elongated strips of rigid material mounted n the upper ends of the passages intermediate the upper edges of the passage forming partitions and with their upper ends flush with the upper ends of the passage forming partitions, and arranged to divide said passages in such a way that the air streams emerging from the passages are unidirec-- tional, expanding in 'a single stream with the' movement of air at some distance from the dif fuser being almost imperceptible while the actual movement in front of the central partition is in the opposite direction to the flow of air therethrough.

12. A ventilating system comprising a chambenf at the upper part of' a first air conduit located said chamber, a diffuser connected to the end of an extension of said conduit, a blower adapted to cause air to flow from the conduit through the diffuser, the diffuser comprising a series of partitions each of the shape of a frustrum of a cone and having successively wider cross section so as to leave diverging passages between said partition to permit air being directed. in expanding streams and dividing means consisting of a framework of elongated strips of rigid material mounted in the upper ends of the passages intermediate the upper edges of the passage forming partitions and with their upper ends flush with the upper ends of the passage forming partitions, arranged to divide said passages in such a way that the air stream emerging from the partitions is unidirectional and expands in a single stream with the movement of air at some distance from the partitions being almost imperceptible while the actual movement in front of the central partitions is in the opposite direction to the flow of air therethrough, a second air conduit remote from the first air conduit and located at the lower part of said chamber, a second diffuser connected to said second air conduit, a second blower adapted to draw air through said second difiuser to said second conduit, the second diffuser comprising a series of partitions each of the shape of a frustrum of a cone except the outer one which is shaped so as to lie flush with a wall, so arranged as to provide a series of converging passages between said partitions to permit air being drawn in from a series of radiating directions and dividing means in the form of elongated strips of rigid material mounted in the upper ends of the passages intermediate the upper edges of the passage forming partitions and with their upper ends flush with the upper 10 ends of the passage forming partitions, and arranged to divide said passages in such a way that the air is drawn unidirectionally in a single converging stream into said passages such that the movement of air at some distance from the par titions is almost imperceptible.

13. A diffuser as claimed in claim 3 in which the partitions consist of a series of truncated conical tubular members concentrically arranged about a common axis and including an inner member defining a central diverging passage, and successive outer members surrounding the inner member and forming a series of annular diverging passages.

THOMAS CHARLES FITT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,973,490 Kurth et a1 Sept. 11, 1934 2,144,631 Kurth Jan, 24, 1939 2,185,919 Kurth Jan. 2, 1 ,4 2,199,525 Kurth May 7, 1940 2,210,589 Kurth Aug. 6, 1940 2,300,049 Kurth Oct. 27, 1942 2,380,553 Serre et a1, July 31, 1945 FOREIGN PATENTS Number Country Date 166,131 Switzerland Mar. 1, 1934 484,523 Great Britain May 6, 1938 566,605 Great Britain Jan. 5, 1945 

